1. Field of the Invention
The invention relates generally to light guide plates for liquid crystal displays (i.e., LCD's) and backlight modules adopting the same and, more particularly, to a light guide plate employing prism elements and a backlight module adopting the same.
2. Discussion of Related Art
Liquid crystal display devices have many excellent performance characteristics, such as large-scale information display ability, easily colored, low power consumption, long life, no pollution associated therewith, and so on. Therefore, liquid crystal display devices are used widely A typical liquid crystal display device generally includes a backlight module, and the backlight module is used to convert linear light sources, such as cold cathode ray tubes, or point light sources, such as light emitting diodes, into area light sources having high uniformity and brightness.
Referring to FIG. 9, a conventional backlight module 10 includes a light guide plate 100, a light source 120 and a prism sheet 900. The light guide plate 100 includes an emission surface 104, a bottom surface 106 and a chamfering 102. The emission surface 104 intersects with the chamfering 102. The bottom surface 106 intersects with the chamfering 102 and is opposite to the emission surface 104. The light source 120 is positioned beside the chamfering 102 of the light guide plate 100. The light source 120 generally is a light emitting diode (LED). The prism sheet 900 is situated upon the emission surface 104 of the light guide plate 100. The prism sheet 900 generally includes a plurality of prisms 902. The prisms 902 are substantially parallel to each other. Each prism 902 is strip-shaped, and a section thereof is a triangle.
In use, incident light beams are emitted from the light source 120 and are transmitted into the light guide plate 100 via the chamfering 102. The light guide plate 100 is used to direct travel of the incident light beams therein and ensure that most of the incident light beams can be emitted from the emission surface 104 thereof The prism sheet 900 can converge the emitted light beams. This convergence helps ensure that the emitted light beams have good uniformity and brightness.
However, a cost of the additional prism sheet 900 is relatively high. This factor increases the manufacturing cost of the backlight module 10. Furthermore, the prism sheet 900 can't adjust the uniformity and brightness of the emitted light beams when the light source 120 is changed.
What is needed, therefore, is a light guide plate which can converge the emitted light beams, according to a potential change in the light source, and which is more economical than the prior combination of a prism sheet and a light guide plate.
What is also needed is a backlight module, adopting the above-mentioned light guide plate.